A known network emulation technology is generally classified into a single-node emulation technology adopting end-to-end network characteristics in a single node and a multi-node emulation technology naturally adopting network characteristics while a packet moves by configured network topology.
The single-node emulation technology is generally implemented as a software module operating in the same host as transmission program and performs emulation before a transmission packet goes out to a network. Since the single-node emulation technology operates in a host, an emulation technology can be easily applied and emulation data can be easily extended through the increase in the number of hosts. On the contrary, since the end-to-end characteristics of the network are applied as an operation result value, reproduction of a queuing delay, a queuing loss, jitter, etc., generated in a queue of a real network node is somewhat vulnerable, and emulation with respect to variations of a protocol environment such as a routing protocol is impossible. The single-node emulation technology is classified into a user mode scheme depending on an application program and a kernel mode scheme operating at a network driver independently from the application program. The user mode scheme is easily implemented, while the user mode scheme has a disadvantage of changing an emulator to suit the changed target application program whenever a target application program is changed or creating the target application program to suit the emulator. Since the packet is intercepted and the emulation is applied at the network driver, the kernel mode scheme can be used as it is even though the application program is changed, but it is difficult to apply a complicated algorithm to the kernel mode scheme.
Meanwhile, the multi-node emulation technology is implemented as an independent emulation device, which is generally connected with a transmission/reception node through a network port, other than operating as a software module operating at the host. Virtual network topology is generated in a system and the network characteristics are applied while the packet moves in accordance with a routing algorithm. A packet transmitted from a transmission node is emulated while it moves through a virtual network and thereafter, it is transferred to a final reception node. Since the virtual network topology is generated and the packet moves through each node, the real network characteristics (queuing loss, queuing delay, jitter, etc.), which were difficult to reproduce in a single-node emulator, are applied. However, since construction of such a system costs a lot and the system is designed for a general network environment test, an additional system should be constructed in order to emulate a large number of packets. As a result, an extension of the system is limitative.